Cool, so if I want to use [email protected] to register on your application I now first have to go to some third party(?*) to verify that [email protected] is valid**. And then, once I've gone through the hassle of that, I have to go back to your website to use the third party service to verify my email. Thanks I guess...
* It's not clear if this service would be provided by a third party (in which case, the problem has merely just been moved) or the email provider. It sounds like the former, but in case it's the latter, then this doesn't have as big an impact I guess.
** While _I_ as the owner of an email address can decisively know that all emails of the form `myname+<whatever>@myemail.com` will go to me, you as the owner of a website attempting to verify my email cannot know that. The standards specify that + is valid in an email user part, but they do not require plus addressing to work.
* It's not clear if this service would be provided by a third party (in which case, the problem has merely just been moved) or the email provider. It sounds like the former, but in case it's the latter, then this doesn't have as big an impact I guess.
** While _I_ as the owner of an email address can decisively know that all emails of the form `myname+<whatever>@myemail.com` will go to me, you as the owner of a website attempting to verify my email cannot know that. The standards specify that + is valid in an email user part, but they do not require plus addressing to work.